Historically, a syndicate was associated with organized crime, as in individuals secretly associating themselves to a criminal plan or organization dedicated thereto.
In contemporary corporate or securities law, syndicates are perfectly legal contracts in which corporations or banks work together - short of incorporation - in regards to a common goal, as in the promotion of a particular stock, mining projects, or the licensing or otherwise managing a particular process, product or service by creating an exclusive club through a contract of syndication.
Syndicate often start off by way of written agreement between the members and evolve, from time to time, to full incorporation, depending on the needs of the members, of the syndicate itself, and of the advantages or disadvantages of the relevant corporate laws within the sphere of operation of the syndicate.